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I'm concerned about the range of the Model S which might limit it's suitability for road trips. Would it be possible to have a trailer hitch with hitch-platform and carry a Honda 240v generator and somehow power the car while driving at highway speeds? I know that this would not look sexy, but it would provide me a level of comfort that I could use the car for more than 160-200 mile trips.

Thanks.

DouglasR | 2013/01/19 - 14:15

There have been other threads on this topic (use volkerize.com to find them). Short answer: no, the car cannot be driven while charging.

Sudre_ | 2013/01/19 - 14:27

Think of it this way. 300 watts per mile average is the least you can expect from the motor. So one hour of driving at 60 mph would be on average 18kWh. Most people are getting more like 380 and above but if you could get 300 watts per mile you would need a generator that can handle a continuous load of 18kWh. The surge peak for the generator would have to be around 300kWh for acceleration. If I recall correctly it's 768 watts per horse power but the motor is three phase so there is formula to calculate the actual number.

If it was so easy to just throw a generator on a trailer the Volt would have been a much easier car to design.

GoTeslaChicago | 2013/01/19 - 14:36

No, but if you put solar cells in front of the headlights you can recharge the battery as long as you drive with the headlights on. : )

DouglasR | 2013/01/19 - 14:43

Sudre, I think you're mixing kW and kWh. The continuous load under your assumptions would be 18 kW, not 18 kWh. It would obviously need more than that as peak capacity, but 18 kW is essentially what you would get from twin chargers using 80 amps @ 240 volts.

The problem is that, towing a trailer, you would consume MUCH more than 300 watt hours per mile (not watts per mile).

ghillair | 2013/01/19 - 14:48

Why not just put the ICE generator in the frunk and call it a hybrid.

O wait that is 20th century.

MarkV | 2013/01/19 - 14:51

As noted already you cannot charge and drive at the same time. Model S also does not allow any sort of trailer connection. Of course you could do something and void the warranty. AAA has instituted a fleet of mobile chargers that will "save" you in a pinch should you get caught.
For the time being (that is before the supercharger network is complete) we just have to adapt to planning better and stopping more frequently when attempting cross country travel. Sort of a throw back to the days when gasoline stations were not on every corner or even in every town for that matter.
You could have a friend or relative deliver your generator to your location if you still want your own unit. Be sure to get a high quality generator because if the sine wave produced is not high enough quality the car will simply reject the connection.

Superliner | 2013/01/19 - 14:51

Really?? that's like having a fuel truck roll along side your ICE and refuel it as you drive!

You could just buy a Honda Civic and use the remaining $80,000 for gas. Or......

Buy a Volt or Karma or "other" Series Hybrid, they already do this.

Superliner | 2013/01/19 - 15:02

@ GoTeslaChicago

Now THAT's a good one BwaaHahahahahaha!! I'll have to remember that for the Generator on the wheel, or wind turbine on the roof crowd. They always seem to forget that any action causes an equal and opposite reaction. So your best outcome is a ZERO sum gain.

Getting Amped Again | 2013/01/19 - 15:04

ghillair | January 19, 2013

Why not just put the ICE generator in the frunk and call it a hybrid.

No that's called a Chevy Dolt.

EK | 2013/01/19 - 15:55

This forum really needs thumbs, or like dislike

like @ GoTeslaChicago

DouglasR | 2013/01/19 - 15:57

You could also just put your Model S on a flatbed truck and drive it around: unlimited range!

Seriously, Honda's biggest "portable" generator is rated at about 9 kW, 37.5A at 240V, and weighs 403 lbs dry. The tank holds 8.1 gal. (another 65 lbs) and it will run for 4.6 hours at rated load. So with a full tank of gas, and 4.6 hours of charging, you could theoretically add 41.4 kWh to the battery. How far that would take you is anybody's guess, but the added weight and drag would surely cut your range way back. Rated energy consumption of about 300 watt-hours/mile works out to 3.3 miles/kWh. If the trailer lowered your mileage by 1/3 to 2.2 miles/kWh, your total range would be 269 miles ((85 kWh * .95 + 41.4) * 2.2)-- about the same as you would get from a range charge without the trailer. In other words, you could drag the trailer for the car's reduced maximum range of around 177 miles, then sit there charging for 4.6 hours to add back 41 kWh, then drag the trailer another 92 miles until you are out of charge again. While it is true that you could probably keep going indefinitely by stopping at a gas station every 80 miles or so and charging for four hours, you would be averaging under 20 miles per hour. Frankly, I'd rather check in overnight at a motel with a charger. Or take a plane.

Brian H | 2013/01/19 - 16:54

GTC +1 works.

TikiMan | 2013/01/19 - 17:00

I'm attaching a giant boat sail to my P85, so I can let it re-gen the battery after 300 miles. Now if I can just set Google maps, so I can avoid all the over-passes, I will be in business!

Brian H | 2013/01/19 - 17:26

Tiki;
More likely in involuntary care, than in business. >:P

shs | 2013/01/19 - 17:34

I own an 18 kW backup generator and it is big and heavy, not to mention the even bigger propane tank that powers it in the case of a grid power failure. It does put in perspective how much power is actually stored in the MS's battery.

The real issue with range and long trips is whether one fills up at a gas station or a supercharger or some other EV charging station. Right now, there are a lot more gas stations and so, for a while at least, serial hybrids may make some sense. I would rather bet on the future though, and go with a BEV and hope that the EV charging fills in the current gaps. (pun intended.)

Superliner | 2013/01/19 - 18:45

@TikiMan

MwaHahaha!! Overpasses? Still.. The laws of physics would reach out to get ya' The wind might move the car but if you add drag as in regen at a rate that would do you any good?? Hmmm How big is that sail again lol!!

Robert22 | 2013/01/19 - 19:35

The sail can be kept small if the military surplus JATO (jet-assisted takeoff) rocket is properly bolted to the chassis...

cprenzl | 2013/01/19 - 19:36

I think that is what superchargers are for, I'm sure you can take another car on your long trips till the end of the year when they cover the US completely

DocDog | 2013/01/19 - 20:49

When I was a small child, I remember my mom running out of gas on numerous occasions b/c she would not plan to get gas when she was getting low, and the nearest (open) station was beyond "the range" in the tank. This is going to happen for a while with electric cars now. Today, running out of gas is quite rare (even for my mom), b/c there is a gas station every 5 miles nearly everywhere we travel. I believe that it won't be long before we have sufficient high amperage electric stations to make "running out of electricity" an unusual event too.

Anthony H | 2013/01/19 - 21:06

@GoTeslaChicago, I laughed.

@pashaw01, I'm sorry. This is a tough audience.

:)

Brian H | 2013/01/19 - 21:58

Robert22;
Which direction was the JATO's thrust vector, again? I intuit you might have a hard time overcoming it with the exhaust hitting the sail ... <;)

Superliner | 2013/01/20 - 00:27

I hope you're kidding Robert, As Brian says if the thrust is directed toward the sail it's a wash .. they apply force to the object in opposing directions "assuming the sail material and mounting structure can withstand the force of jet exhaust" not to mention the heat lol!! One more for the Generator on the wheel theory! BaHahahaha! Physics will not allow a free lunch.

Brian H | 2013/01/20 - 00:52

Like the old idea of blowing on the sail in a sailboat. The only way blowing would help is if you made like a jet engine and blew backwards, probably spinning around to inhale facing forwards, and repeat. You could combat the serious hyperventilation by swinging a sweep oar back and forth all the while, to help.

Take lots of time out to eat; you'll probably burn 6-10,000 Calories a day! Lots of Big Macs, supersized fries, and milkshakes would probably do it. Every couple of hours.

Timo | 2013/01/20 - 03:24

@Brian H, Like the old idea of blowing on the sail in a sailboat.

Mythbusters tested that. For their surprise sailboat did move forward with fan blowing to the sail at the back of the boat (and it did work in any direction in that lake, so this was not a case of actual wind blowing to the sail).

I think the Mythbuster thing actually worked like an air-boat except the air was ricochet'd off the sail. It would have worked better to just turn the fan around and let the air-boat work normally.
If you take a fan and connect a giant 20' long rubber hose to the output of the fan the boat will go opposite where ever you point the rubber hose no matter where the fan actually is..... much like a rocket.

Sometimes I really wish it wasn't so hard getting the crazy Monty Python circus act out of my head and onto paper.

pashaw01 | 2013/01/20 - 08:41

This is great fun, thanks for the replies all! I expected much worse...

Physics prevents it. You simply cannot extract enough energy from the propulsion force of a vehicle "or any vehicle" to make self sustaining motion. Any drag introduced to generate energy is directly opposed to propulsion therefore you need to use more energy to overcome the added drag and remain in steady motion. The additional energy consumed to overcome generation drag offset hence a zero sum gain.

If it were that easy we would all be driving perpetual motion cars.

Brian H | 2013/01/20 - 12:20

How much power is delivered to the fan blades? How efficient is the forward motion? Lots, and not very.

edpalermo | 2013/01/20 - 14:27

That is a ridiculous question, IMHO .

Timo | 2013/01/20 - 14:35

@edpalermo, which question? We are talking about sails in roof of a car, so I think any question about that concept is going to be ridiculous. I think that is the point.